Active agent delivery devices are used to release active agent over a prolonged period of time, or, when the active agent is a fire starting fluid, over a period of time sufficient to ignite combustible material. Many different types of absorbents have been disclosed for slow release of active ingredients such as fragrances or insect repellents.
Levy, in U.S. Pat. No. 5,858,384, discloses silicates that can be used in blocks to trap insecticides for slow release of the insecticides into a body of water. While many different types of porous carriers can be used for this purpose, the preferred materials are silicates which have a surface area of from about 50 to 450 m2/g, an average agglomerate size of from about 3.5 to about 100 microns or an average particle size of from about 12 to 39 nanometers, a tapped density of from about 50 to about 240 g/l, a pH of from about 3.6 to about 9, and a DHP adsorption of about 160 to 335 g/100 g.
Murray et al., in U.S. Pat. No. 4,020,156, disclose fragrance releasing beads comprising a water-soluble particulate carrier coated with a finely divided inorganic matrix containing the fragrance. This matrix may be calcium silicate.
Breitenbucher et al., in U.S. Pat. No. 5,573,984, disclose porous glass bodies for storing volatile substances so as to permit a regulated evolution of the substances.
Mosbaugh, in U.S. Pat. No. 6,245,733, teaches an agglomeration of fused microspheres that can be used to absorb oil or alcohol-based liquids. This can be used as a long term fragrance delivery for slow release of fragrance.
Lang et al., in U.S. Pat. No. 5,032,549, disclose using calcium silicate granules in animal litter and bedding. The calcium silicate is said to have a microporous structure, which as a result of capillary action, is able to absorb oleophilic and hydrophilic liquids as well as gases.
Che et al., in U.S. Pat. No. 4,788,164, disclose sustained release composition consisting of an inorganic oxide glass monolith and a microporous volume that contains a volatile organic component and a nonvolatile organic component. The volatile organic component can be a fragrance, an insect repellant, or a fish attractant.
Chakrabarti et al., in U.S. Pat. No. 5,035,886, discloses active agent delivery devices comprising a microporous material of a matrix of an ultrahigh molecular weight polyolefin, a large amount of filler, at least 50% of which is siliceous, and a releasable active agent.